Dengue in Brazil: reflections about the largest epidemic in the world and impact of the reduction of
mortality
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Glena F. Rossi1, Darlene C.A. Morandim , Ana TeresaR-Viso
Faculty of Medicine, University of Ribeirão Preto (UNAERP) Sixth year medical students, UNAERP, Infectologist Professor of UNAERP Corresponding author:
[email protected]
.
Introduction: Dengue is an acute febrile disease of
viral etiology with a benign course in the classical form
and a severe course in the hemorrhagic form. Today,
dengue is considered to be the most important
arbovirus infection affecting humans. It represents a
serious Public Health problem worldwide, especially in
countries of tropical and subtropical climate, where
environmental conditions favor the development and
proliferation of its vectors, Aedes aegypti and Aedes
albopictus. Four serotypes of dengue virus are known,
denoted DENV 1, DENV 2, DENV 3 and DENV 4, all
of which can cause either the classical and harmless
form of the disease or the more severe one. The
clinical signs of classical dengue vary widely, but the
main manifestation is fever, usually high and of abrupt
onset, followed by headache, myalgia, prostration,
arthralgia, anorexia, asthenia, retro-orbital pain, nausea,
vomiting, and exanthema predominantly of the
maculopapular, accompanied by skin itching. The
disease lasts 5 to 7 days.
Brazil is a tropical country covered by extensive native
forests, with a rapid and disorderly growth of cities
that have led to the construction of human dwellings
very close to natural areas, an environment favoring
the dissemination of mosquitoes.
Objective: Describe and analyze the epidemiology
of dengue in Brazil until 2014.
Materials and methods: We analyzed several
publications by the Health Ministry, as well as data
from the Brazilian Institute of Geography and Statistics
and literature reviews (PubMed). The major document
source used was the monitoring of the Health
Ministry’s Epidemiology u to the25th week of 2014,
consulted through the internet.
Description of the epidemiological data of
dengue in Brazil: The dengue virus was first
detected in Brazil as an outbreak in Roraima (North
region) in 1981-82, with the presence of serotypes 1
and 4.
The first dengue epidemic in Brazil took place in Rio
de Janeiro (Southeast region) in 1986-87, with about
90 thousand cases. During 90 decade, the circulation
of the DENV-1 and DENV-2 serotypes spread rapidly
to other areas of the Brazilian territor y,
accompanying the dissemination of the vector
mosquito and in 1998 Brazil recorded 700 thousand
dengue cases. The DENV-3 serotype was responsible
for the 2002 epidemic in Brazil, when approximately
800 thousand cases were notified, i.e., almost 80% of
all cases on the American continent. In 2008, more
than 700 thousand dengue cases and more than 45
thousand hospitalizations due to the disease were
recorded by the Health Ministry of Brazil.
Over the last 50 years, the incidence of dengue has
shown a 30-fold increase in the world, with a
geographic expansion to new countries and to small
towns and rural areas occurring during the current
decade. The WHO estimates that almost half the
world population lives in countries were dengue is
endemic, and Brazil occupied first place among the
30 countries with the largest number of cases in the
world from 2004 and 2010.
Dengue epidemic in 2013: The greatest dengue
outbreak in Brazil occurred in 2013, with
approximately 2 million cases notified. Table 1 shows
that 616,387 cases of dengue had been notified in
Brazil up to June 21, 2014. The largest number of
cases occurred in the Southeast region, followed by
the Center-West, Northeast, South and North
regions. The Southeast was the region with the
largest number of registered serious cases with alarm
signals, with 242 deaths confirmed in 2013 and 85
confirmed up to June 2014. Considering all regions of
Brazil, there were 6,048 serious cases in 2013, 328 up
to June 2014, 4,873 cases with alarm signals, 519
confirmed deaths in 2013, and 209 in 2014,
corresponding to a 60% reduction of deaths for the
country as a whole. The serotype distribution was:
80.1% DENV 1, 17.7% DENV4, 1.8% DENV2, and
0.4% DENV3.
Table 1. Number of dengue cases notified and incidence
per 100,000 inhabitants according to each region and
State of Brazil, 2013 and 2014
Region/State
EW 1 to 25
Incidence (/100,000 inhab.)
2013a
2014b
2013a
2014b
43,958
30,401
258.4
178.7
Rondônia
8,512
2,969
492.5
171.8
Acre
2,347
4,725
302.3
608.5
15,445
7,596
405.6
199.5
430
652
88.1
133.6
Pará
8,222
5,917
102.8
74.0
Amapá
1,502
951
204.4
129.4
7,5
7,591
507.4
513.5
Northeast
115,368
68,156
206.8
122.2
Maranhão
2,827
1,942
41.6
28.6
Piauí
3,667
4,659
115.2
146.3
Ceará
19,144
19,267
218.1
219.5
Rio Grande
do Norte
11,631
6,841
344.7
202.8
8,574
4,248
219.0
108.5
6
9,134
65.2
99.2
Alagoas
6,143
5,726
186.1
173.5
Sergipe
444
2,032
20.2
92.5
North
Amazonas
Roraima
Tocantins
Paraíba
Pernambuco
Bahia
56,938
14,307
378.5
95.1
Southeast
898,481
358,684
1.063.7
424.7
Minas Gerais
413,249
74,603
2,006.7
362.3
Espírito Santo
61,443
17,063
1,600.3
444.4
207,586
9,142
1.268.2
55.8
216,203
257,876
495.2
590.6
South
66,709
44,851
231.7
155.8
Paraná
65,935
44,045
599.5
400.5
349
403
5,3
6.1
425
403
3.8
3.6
Center-West
249,441
114,295
1,663.7
762.3
Mato Grosso
do Sul
77,422
6,364
2,992.4
246.0
Rio de
Janeiro
São Paulo
Santa
Catarina
Rio Grande
do Sul
Mato Grosso
Goiás
Federal
District
Total
32,231
7,944
1,012.9
249.6
129,433
87,147
2,011.7
1,354.5
10,355
12,84
371.2
460.3
1,373,957
616,387
683.3
306.6
bEW
= epidemiological week
Source: BRASIL, 2014
Discussion: The Health Ministry promoted
campaigns through various media (television,
posters, health stations) in order to instruct the
population to prevent the occurrence of stagnant
water reservoirs in 2014. Health agents
systematically visit homes in highly endemic areas
in order to detect possible mosquito breeding
sites. The strategies for dengue control are being
periodically revised in Brazil as qualification in
clinical management; application of larvicides and
adulticides; improvement of alert and response
ability with access to information in real time
since all suspected of dengue are notified.
An innovative measure undertaken in Brazil was a
technique for the sterilization of Aedes aegypti
mosquitoes with the introduction of transgenic
mosquitoes, preventing dissemination of the virus.
It was implemented in 2014, but its impact can be
analyzed only in the medium or long term.
Another mosquito modified with a bacterium that
prevents infection with the dengue virus has been
recently introduced in Rio de Janeiro, also with a
medium- or long-term impact.
According to the perspective of the WHO,
measures of dengue control were expected to be
able to reduce mortality and morbidity by at least
50 and 25%. Comparison of data for 2013 and
2014 (up to June) revealed a 60% reduction of
deaths in Brazil, exceeding the goal of the WHO
and revealing the impact of the measures adopted
regarding this important reduction of deaths.
The dry climate during this period may have
contributed to a reduced dissemination of the
mosquito and consequently of the transmission of
the disease. However, the fact remains that there
was an effective decrease of morbidity and
mortality in Brazil and that the reduced number of
deaths was probably due to the implementation of
various measures in all health, prevention and care
spheres, as described above.
Conclusions
The reduction of the number of deaths in the first
semester of 2014 had an important impact in
Brazil, showing that the efforts to control dengue
should be maintained, even though the most
challenging problem is to change the habits of the
population and to hold it responsible for the
domiciliary accumulation of water.